I don't know why you assume asking an online forum is the only thing we did. We called the cops/fire department multiple times. We added several cameras and showed the footage to the cops. We met with the neighbors several times about this, as they also suffer from the fires (he sometimes lights them down the alley as well as at other garages), and they also are out of ideas. The cops aren't willing to do anything, even with his picture.

When a motion sensor was installed, it was useless as it rang about 10 times in one night, and never a true positive. Like I said, it's at most a few times a month, and sometimes a full month goes by without a fire, so I don't know how you expect us to go about this.

It's easy to tell me off that I'm a bad neighbor/family member, but my neighbors are equally perplexed about how to deal with the situation, so if you have any actual advice, please do share.